Hydraulic self-adjusting rocker arm



1958 4 c. F. YANDT- 2,818,845

HYDRAULIC SELF-ADJUSTING ROCKER ARM 5 Shee ts-Sheet 1 Filed Oct. 17, 1955 5 in I v 39 4| I CARL E YAN DT Jan. 7, 1958 Y c. F. YANDT 2,318,845

HYDRAULIC SELF-ADJUSTING ROCKER ARM Filed 001;. 17, 1955 s Sheets-Sheet z INVENTOR CARL F. YANDT ATTORNEY Jan. 7, 1958 c. F. YANDT 7 HYDRAULIC SELF-ADJUSTING ROCKER ARM Filed Oct. 17,1955

3 Sheets-Sheet 3 7 mvsufon CARL F. YANDT 7 fiLAfl/ a.

' ATTORNEY nited tates 8 Claims. (Cl. 123-90) This invention relates generally to valve operating rocker arm assemblies for internal combustion engines and more specifically to such a rocker arm assembly which is self adjusting in nature under hydraulic forces.

The primary object of this invention is to provide a two-piece pivotally interconnected rocker arm assembly with an hydraulic clearance take-up unit between the pieces to eliminate objectionable clearances between the push rod and the valve stem of an internal combustion engine.

Another object of this invention is to provide an bydraulic take-up unit for a two-piece pivotally interconnected rocker arm assembly for internal combustion engines which may be quickly removed for servicing or replacement by an unskilled mechanic.

A still further object of this invention is to provide a two-piece pivotally interconnected rocker arm assembly with an hydraulic clearance take-up unit connected between the pieces and responsive to engine lubricating oil pressure to automatically eliminate objectionable clearances between the push rod and the valve stem of the engine.

Another object of this invention is to provide a twopiece pivotally interconnected rocker arm assembly with an hydraulic clearance take-up unit connected between the pieces which is economical to manufacture and relatively simple to install on an internal combustion engine.

A further object of this invention is to provide an effective hydraulic take-up unit for a one-piece rocker arm which may be readily installed on or removed from an engine.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims, certain embodiments and details of construction of which are illustrated in the accompanying drawings in which:

Figure 1 is a view in side elevation of the rocker arm assembly in its operative position between the push rod and the valve stem of an internal combustion engine, a portion of which is shown in section;

Figure 2 is a plan view of the rocker arm assembly including a portion of the supporting pipe;

Figure 3 is a sectioned view in side elevation of the rocker arm assembly taken along the lines 33 of Figure 2;

Figure 4 is an exploded view of the rocker arm assembly showing the various parts thereof in perspective;

Figure 5 is a view in side elevation of a rocker arm assembly which constitutes a modified form of the invention;

Figure 6 is a view in side elevation of a one-piece rocker arm assembly in its operative position between the push rod and the valve stem of an internal combustion engine, a portion of Which is shown in section, with a modified form of hydraulic take-up unit applied to the rocker arm assembly;

Figure 7 is an enlarged fragmentary view in section of atent 2,818,845 Patented Jan. 7, 1958 a portion of the rocker arm and of the modified hydraulic take-up unit illustrated in Figure 6.

Referring more particularly to Figure l, the rocker arm generally indicated at 1 is illustrated in its operative position on an engine. The rocker arm consists of parts 2 and 3 pivotally interconnected about abushing 4. The lower bearing surface 5 of the part 2 engages the capped upper end of valve stem 6 of valve 7 mounted in the engine 8. The part 3 of the rocker arm has a lower bearing socket 9 of hemispherical form to engage the upper end of engine push rod 10 which is curved to fit the socket. When the push rod 10 is operated upwardly by engine cam 11 the movement is transmitted through the rocker arm 1 to the valve stem 6 to unseat valve 7 against the biasing action of spring 12.

In order to transmit the movement of the push rod 10 through the rocker arm 1 to valve stem 6 without any lost motion it is essential to provide an automatic clearance adjusting device with the rocker arm which will maintain the two bearing surfaces 5 and 9 in constant and firm contact with the valve stem and the push rod. This is accomplished in the present invention by means of an hydraulic take-up unit indicated generally at 13. The unit 13 consists of a cylinder 14 pivotally connected at one end about a pivot pin '15. The pin 15 is carried by upstanding spaced ears 16 and 17 of part 2 of the rocker arm. A cotter pin 18 or other suitable means retains the pivot pin in assembled position. Within cylinder 14 is a piston 19 which is constructed for a close fitting, sliding relationship therewith. Piston 19 is provided with an extended portion 20 terminating in a knob 21 which is received in a co-fitting bearing socket 22 on upstanding portion 23 of part 3 of the rocker arm.

The piston 19 is normally urged outwardly of the cylinder 14 by means of a coil spring 24. The piston 19 is provided with an enlarged cavity 25 terminating in a tapered wall 26 which acts as a seat for a ball check valve 27. Valve 27 is urged against the seat 26 by a coil spring 28 which is retained within the cavity 25 by a split ring retainer 29 mounted in a groove 30 on the inner wall of the piston 19. The valve 27 is utilized to prevent reverse flow from the interior of the take-up unit 13 through the passage 31 in extended portion 20 of piston 19.

The part 3 of the rocker arm is provided with three joined oil passages 32, 33 and '34 leading respectively to the socket 22, the socket 9 and to the aperture 35 for the bushing 4. The sockets 9 and 22 are thus maintained constantly lubricated. Bushing 4 as seen in Figures 3 and 4 is provided with a reduced section 36 midway of its extremities. The reduced section 36 is provided with ports 37 and 38 leading to the interior of the bushing. Bushing 4 is carried on a hollow pipe member 39 which acts to support the various rocker arm assemblies on the engine and to supply lubricating oil under pressure to the takeup units of each rocker arm of the engine. In Figure 3 the spacing between the pipe 39 and bushing 4 is indicative of an undercut section on the exterior of pipe 39 to assure continuous fluid communication between the interior of the pipe and the bushing ports 37 and 38. Pipe 39 is provided with ports 40 and 41 leading from its interior to the interior of the bushing. Thus it becomes obvious that lubricating oil is conveyed from pipe 39 through bushing 4 to passage 34 and thence to passages 32 and 34 in rocker arm part 3.

The operation of the rocker arm 1 should now be obvious to one skilled in the art. With the engine in operation, and the cam 11 rotating, the push rod 10 will be periodically raised to rock the rocker arm assembly 1 about the bushing 4 in a counterclockwise direction. Since the part 2 of the assembly is in contact with the valve stem 6, then valve 7 will be raised from its seat. To automatically compensate for any lost motion between the cam movement and the valve moyemengthe take-up unit 13 will adjust the relative positions of the parts 2 and 3 of the rocker arm assembly 1 about the bushing 4. The. take-up. unit, 13. receives oil under pressure f om passage 32 in rocker arm part 3.. Valve 27 is set to unseat to. maintain a. predetermined amount of pressure within the unit 13. Thus if the pressure within the unit drops below the desired level the valve 2.7 will unseat and engine oil, under pressure will be admitted. Therefore it is now obvious. that the, take-up unit 13 is operative both hydraulically andv under the influence of spring 24 to urge the parts 2 and 3 in opposite. directions about their pivot bushing 4. to automatically compensate for any lost motion between the push rod cam 11 and the valve stem 6.

In Figure a modification is illustrated which is suitable for engines wherein the spacing between the valve stem and the push rod is greater and, hence a longer rocker arm is required. In the form shown the same takeup unit 13 may be utilized. The, rocker arm assembly 42 in this form consists of parts 43 and 44 pivotally interconnected by a pin 45. The part 44 is then pivotally carried by a bushing 4. as in the preferred form. The operation of this form. will be identical to that of the preferred form.

Another modified form of the invention is disclosed in Figures 6 and 7. This modified form includes. a similar but modified form of hydraulic take-up unit 46 connected by a U-bolt 47 and nut 48 to a depending flange 49 of a single piece rocker arm 50. The arm 50 is pivotally carried by a bushing 51 similar to the bushing 4 of the preferred form or" the invention. The arm 50 is. rocked about pivot bushing 51 by an engine push rod 52 having a head 53 engaging in a socket 54 adjacent one end 55 of the arm.

The take-up unit 46 comprises a Cylinder 56 terminating at one end in an extended curved head 57 which engages a similarly curved socket 58 in end portion 59 of rocker arm 50. The head 57 of cylinder 56 is provided with a port 60 which coacts with passages 61 and 62 in arm 50 to receive engine oil under pressure from the ported bushing 51 as in the preferred form. A check valve 63 seats against the tapered seat 64 interior of the head 57 and is biased against the seat by a coil spring 64 retained in the head by a split retaining ring 65.

The take-up unit of Figures 6 and 7 is further provided with a piston 66 which is in relatively close fitting sliding relationship with the cylinder 56. The piston 66 is normally urged outwardly of the cylinder 56 by a coil spring 67 and by the engine oil under pressure. The outer surface 68 of the piston 67 engages the upper end of a valve stem 69 under the pressure of both the .oil and the spring 67.

The operation of this modified form of the invention in Figures 6 and7 is similar to that of the preferred form. When the cam 70 raises push rod 52 the rocker arm 50 will be rocked clockwise to press downwardly on valve stem 69 to open valve 71. The valve spring 72 returns the parts to the position shown in Figure 6. Any tendency of the parts to develop a lost motion resulting in valve noise or engine inefiiciency is immediately compensated for by the take-up unit 46, the piston 67 of which is ready at all times under fluid pressure to extend further from cylinder 56 to eliminate clearances.

The take-up units 13 and 46 of the forms of the invention illustrated may be readily removed for servicing or replacement by an unskilled mechanic. For example, in the preferred form of Figures 1 to 4 and themodified form of Figure 5 it is only necessary to remove the pivot pin 15 to release the unit 13. In the form of Figures 6 and 7 it is only necessary to remove the U-bolt 47 to release the unit 46.

It is readily obvious that this invention may be subject .to certain other structural modifications well within the knowledge of this inventonand hence it isintended that the invention and its ramifications be limited only by the scope of the claims. One of the more obvious modifications in the structure would be the substitution of a spring operated take-up unit for the hydraulic unit of the invention. This and other obvious changes are well within the purview of the inventor.

I claim:

1. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, one of said parts having a pair of upstanding ears, the other of said parts having an upstanding portion with a socket therein, and an hydraulic take-up unit pivotally connected at one extremity to the upstanding ears of the said one part of the rocker arm and having its other extremity removably engaging the socket in the upstanding portion of said other rocker arm part.

2 A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, the first of said parts having an upstanding portion, the second of said parts having an upstanding portion with a socket therein, and a take-up unit pivotally connected at one extremity to the upstanding portion of said first part of the rocker arm and having its other extremity removably engaging the socket in the upstanding portion of said second part of the rocker arm.

3. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, the first .of said parts having an upstanding portion, the second of said parts having an upstanding portion with a socket therein and an hydraulic take-up unit pivotally connected at one extremity to the upstanding portion of said first part of the rocker arm and having its other extremity removably engaging the socket in the upstanding portion of said second part of the rocker arm.

4. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, the first of said parts having an upstanding portion, the second of said parts having an upstanding portion with a socket therein, an hydraulic take-up unit pivotally connected at one extremity to the upstanding portion of said first part of the rocker arm and having its other extremity removably engaging the socket in the upstanding portion of said second part of the rocker arm, and means to convey oil under pressure to said hydraulic take-up unit from said pivotal interconnection between said rocker arm parts.

5. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, the first of said parts, having an upstanding portion, the second of said parts having an upstanding portion with a socket therein, an hydraulic take-up unit including a cylinder and a piston slidably received in the cylinder and having an extended portion terminating in a knob and being provided with a passageway from the knob through the piston, the cylinder being pivotally connected to the upstanding portion of said first part of the rocker arm, the knob of said piston engaging the socket of the upstanding portion of said second rocker arm part, and means to convey oil under pressure to said hydraulic takeup unit from said pivotal interconnection between said rocker arm parts.

6. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm formed by two pivotally interconnected parts, means to pivotally interconnect one of said parts to the engine and ,an hydraulic take-up unit removably interconnected between said parts above both said pivotal connections relative to the engine.

7. A rocker arm assembly for operating a valve in an internal combustion engine comprising a rocker arm .5 formed by two pivotally interconnected parts each having upstanding portions thereon, means to pivotally interconnect one of said parts to the engine, and a take-up unit removably interconnected above both said pivotal connections relative to the engine.

8. A rocker arm assembly for operating a valve in an internal combustion engine comprising a supporting pipe connected to the engine, a rocker arm formed by two pivotally interconnected parts, said' rocker arm parts having their pivotal connection about said pipe, one of said parts having a pair of upstanding ears, the other of said parts having an upstanding portion with a socket therein, and an hydraulic take-up unit pivotally connected at one extremity to the upstanding ears of the said one part of the rocker arm and having its other extremity 6 removably engaging the Socket in the upstanding portion of said other rocker arm part.

References Cited in the file of this patent UNITED STATES PATENTS 1,333,160 Cline Mar. 9, 1920 1,445,287 Bradburn Feb. 13, 1923 1,536,221 Kelley May 5, 1925 1,931,476 Hallett Oct. 17, 1933 2,041,983 Van Ranst May 26, 1936 2,053,743 Russell Sept. 8, 1936 2,380,051 Kettering July 10, 1945 2,764,141 Schoonover Sept. 25, 1956 2,765,783 Randol Oct. 9, 1956 

